Refining hydrocarbon oils



Patented Nov. 15, 1 938 UNITED STATES PATENT OFFICE REFINING HYDROCARBON. OILS Francis X. Govers, Vincennesf Ind assignor to Indian Refining Company, Lawrenceville, Ill., a

corporation of Maine No Drawing. Application December '27,

Serial No. 648,988

4 Claims.

This invention relates to refining hydrocarbon oils and more particularly to refining mineral oil for the production of high viscosity index, low pour test lubricating oils.

Broadly, the invention contemplates the treatment of hydrocarbonoils, particularly parafiinbearing lubricating fractions of petroleum, with solvents to selectively produce therefrom low pour ..test lubricating oils characterized by havinga phur dioxide,- provide a mixture having a selective "solvent action on the various constituents of the oil; a

I have found that mixtures of liquid sulphur dioxide with methylene. chloride are particularly well adapted to the treatment of wax-bearing lubricating oil fractions for the production of low pour test high viscosity index lubricating oils which are also characterized-by having a low sulphur content and low carbon residue content.

Lubricating oil fractions derived from mixedbase crudes, for example, in addition to containing wax constituents, usually also contain unde- 1 sirable constituents of the nature of aromatic and unsaturatedbodies as well as sulphur-bearing.

bodies. They are also composed of various hydrocarbons, or groups of hydrocarbons, some of which are of a more paraflinic nature, while others are of a more naphthenic nature. The former are characterized by having a. fiat temperature-viscosity relationship, or highviscosity index, while the latter are characterized by having a relatively steep temperature-viscosity relationship, or low viscosity index. The relatively high viscosity index constituentspossesssuperior lubricating qualities for many purposes, as, for example, for the lubrication of internal combustion engines and the like.

oxide to methylene chloride "during successive extractions, it is possible to separate the oil into fractions ofdiffering viscosity index.

By treatment of the lubricating oil fractions with the foregoing solvent liquids, mixed in proper proportion, lubricating oils of any desired viscosity index and scale of purification can be obtained from mixed-baseor paraffiin-base crude, and the oils so produced are characterized further by low carbon residue and low sulphur content. The obtaining of oils having these desired qualities does not depend on methods involving.

redistillation or acid treatment. In general, the

oils obtained by my process require no refining with sulphuric acid with its attendant undesirable high losses in valuable lubricating oil constituents as well as its consequent production of diflicultly disposable acid sludge.

The following example will serve to illustrate the application of my invention to the treatment ofa wax-bearing lubricating oil distillate derived from Mid-Continent crude by Vacuum distillation, and having the following characteristics:

Gravity A. P; I 24 Saybolt Universal viscosity 210 F 65 Pour point "F 85 This distillate is first subjected to dewaxing which may be accomplished by mixing about one part of the distillate with about two and one-half parts of a solvent mixture comprising about ten parts of liquid sulphur dioxide and ninety parts of 7 methylene chloride. The mixture is chilled to the desired dewaxing temperature which may be around 0,F. or below in order to precipitate the wax. The precipitated wax is then sepa-.

rated from the mixture advantageously by filtration.

The oilfiltrate mixture resulting from the foregoing dewaxing step is then subjected to further treatment for the separation of the low viscosity index and other undesired constituents. For this purpose, an additional quantity of liquid sulphur dioxide :is added to thereby. produce a solvent mixture with the oil containing the liquid sulphur dioxide and methylene chloride in about equal proportions by volume.

The mixture, if not already cold, is cooled to about 0 F. and allowed to separate into two layers. The' lower layer comprises naphthenic bodies of low viscosity index dissolved in the solvent liquid. This layer is removed and the solvent liquid recovered therefrom.

The upper layer, or the fraction remaining from the above separation, comprises the parafiinic 25 teristics of those described above.

and relatively high viscosity index portion of the oil mixed with a relatively small amount of solvent liquid. This portion, designated as fraction A, may then be subjected to further treatment 5 with additional quantities of the solvent liquids in order to separate it into fractions of differing viscosity index.

For example, the fraction A may be treated with four parts by volume of a selective solvent l mixture composed of about forty percent liquid sulphur dioxide and sixty percent methylene chloride. This mixture is then chilled to around F. and allowed to settle into two layers which are drawn off separately and the solvent removed from each.

The 'upper layer resulting from this extraction, after removal of the solvent, will comprise an oil having a specific gravity of about 29.4" A. P. I. with a viscosity index of about 98. The lower layer, after removal of the solvent, will comprise Q Furthermore, the invention is not limited to the treatment of wax distillate, such as given in the example herein, but is adapted to the treatment of other parafiin-containing fractions, precipitate's', wax concentrates, or materials, somewhat similar in nature, derived in various ways from mineral oils. It is also applicable to the treatment and purification of crude petroleum from different fields, as well as to various distillate or residual 'fra'ctions, including naphtha,

40 kerosene, etc.; that may be derived from the crude.

For example, my invention is applicable to the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials,-"or'mineral oils, including liquid or solid hydrocarbonfractionsderived from mineral oils.

"Hydrogenation products may contain substantial quantities of waxy or parafiin material as well as other constituents of relatively low lubricating value; By treating such products in accordance with my invention, final products of desired char- 'acteris'tics can be obtained.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

Iclaim: 1. The method of manufacturing low pour test high viscosity index lubricating oil from waxbearing mineral lubricating oil stock such as derived from Mid-Continent crude comprising mixing about one part of the oil with about two parts of a mixture of sulphur dioxide and methylene chloride containing around 10% sulphur dioxide,

"chilling the mixture to a temperature of 0 F.

and below to precipitate wax, removing the wax thus precipitated, adding to the dewaxed mixture further sulphur dioxide to produce a solvent mixture containing up to about 50% sulphur dioxide, separating the mixture while at a temperature of around 0 F. into extract and raflinate phases, removing the resulting phases and removing the solvent therefrom.

2. The method of. manufacturing low pour test oil having a viscosity index of and above from wax-bearing lubricating oil stock such as derived from Mid-Continent crude comprising mixing about one part of the oil with about two parts of a mixture of sulphur dioxide and methylene chloride, containing around 10% sulphur dioxide, chilling the mixture to a temperature of 0 F. and below to precipitate wax, removing the wax thus precipitated, adding to the dewaxed mixture further sulphur dioxide to produce a solvent mixture containing about equal parts of sulphur dioxide and methylene chloride, separating the mixtu're'of oil and solvent while at a temperature of around0 E. into extract and rafiinate phases, removing the extract phase, subjecting the raflinate phase to further phase separation in the presence of a solvent mixture composed predominantly of methylene chloride, thereby forming secondary extract andraffinate phases, removing said secondary phases and removing the solvent therefrom.

3. In the manufacture of mineral lubricating oil, the method which comprises mixing waxbearing mineral lubricating oil containing relatively low'and relatively high viscosity index constituents with sulphur dioxide and methylene chloride in proportions such that the mixture has selective action as between wax and oil at temperatures of around 0 F., chilling the mixture to precipitate wax, removing the wax thus precipitated to produce a dewaxed mixture of oil and solvent, modifying the solvent composition of the dewaxed mixture, separating the mixture into an extract phase containing low viscosity index constituents, and a raffinate phase containing high viscosity index constituents, and separating the two phases.

4. In the manufacture of mineral lubricating oil, the method which comprises mixing waxbearing mineral lubricating oil containing relatively low and relatively high viscosity index constituents with an extraction solvent having relatively high selectivity as between low and high viscosity index constituents and methylene chlorideinjproportions such that the mixture has selective action as between wax and oil at temperatures of around 0 F., chilling the mixture to precipitate wax, removing the, wax thus precipitated to produce a dewaxed mixture of oil and solvent, modifying the solvent composition of the dewaxed mixture, separatingthe mixture into .an extract phase containing low viscosity index constituents, anda raffinate phase containing high viscosity index constituents, and separating the two phases.

FRANCIS X. GOVERS. 

